Artificial tooth and process of making same.



B. E. ELDRED. ARTIFICIAL TOOTH AND PROCESS OF MAKING SAME.

APPLICATION FILED JUNE 23, 1909.

1 1 33 atanted Mar. 30, 1915.

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BYRON E. ELDRED, OF BRONXVILLE, NEW YORK.

ARTIFICIAL TOOTH AND PROCESS OF MAKING SAME.

Specification of Letters Patent.

Patented Mar. 36, f9f5.

Application filed June 23, 1909. Serial No. 503,888.

To all whom it may concern Be it known that I, BYRON E. Ewan, a citizen of the United States, residing at Bronxville, in the county of Westchester and State of New York, have invented certain new and useful Improvements in Artificial Teeth and Processes of Making Same, of which the following is a specification.

This invention relates to artificial teeth and processes of. making same; and it comprises an artificial tooth of baked ceramic material having an inset base metal anchor element spaced awa from said ceramic material; and it comprises a method of producing such teeth by positioning an anchor ele ment comprising a base metal in a suitable tooth mold, positioning ceramic material about but out of contact at any point with the base metal of said anchor element, and

molding it'into shape thereabout and baking the whole at the desired temperature; all as more fully hereinafter set forth and as claimed.

Artificial teeth are usually made of a baked ceramic material, a composition being chosen having a color simulating that of a natural tooth. The ceramic material is usually a silicious material containing silica, feldspar, fluorspar, kaolin, etc., together with coloring agents, the coloring agent very often com- Usually the tooth is first biscuited and then fired at a very high temperature, rang-in from 1800 to'27 00 F. Thetooth soma e is usually provided with an inset anchor element to facilitate fastening later. Most of the base metals will not withstand the high temperatures of the baking operation and the action of thesilica, etc. Platinum is very often used and while this withstands the high temperature, it is a soft, weak metal. The use of compound pins composed of a core of a stiff and strong metal, such as nickel, and a sheath of platinum has been suggested for anchor elements; but it has been found by experience that these anchor elements do not work successfully. The compound metal anchor element is usually a cut wire section on which at the end both the base metal core and the platinum are exposed. On baking such an element into a tooth it is found that there is a development of gas, causing cavities at the'inset base of the pin, rendering the tooth useless. Neither a nickel pin nor a platinum pin does this. I have found that this development of gas may be obviated and sound teeth containing compound metal anchor elements may be made by the expedient of spacing away the base metal element from .the surrounding tooth material prior to'baking. With a platinum sheathed nickel pin, the platinum separates it along the length of the pin. At the inset end of the pin, I

provide a further protection by placing a protective layer of inert mineral matter thereupon, covering the naked end of the pin. Thereafter I mold the tooth plastic about the anchor and fire the molded tooth. The compound metal anchor element should have the platinum weld-united to the core of stiff and strong metal.

As my invention is usually carried out, I first produce a tooth pin from a pit of platinum coated wire by heading one or both ends in an ordinary pin-making machine. This is then placed in position through a suitable orifice in a tooth mold projecting into the mold cavity with a headed'base end inward and with the bare spot in the head where the core is exposed protected against coming into contact with the, tooth plastic arabic or with water alone, and painted onthe bare spot. As the oxids of the common strong metals, such as nickel, cobalt and iron, are basic in their nature, these indifferent or basic oxids which are so used as a protective agent have no tendency to cause oxidation of the strong metal or to dissolve the oxid which may alreadv'be present, with the production of fusible staining compounds. Nor can they aid in the production of a galvanic couple between the strong and electrically positive metal and the platinum since the strong metal does not tend to form an anode in their presence.

If desired, in forming the pin head the tool may be-somewhat modified so as to produce a sort of cupping in the head adapted to receive the layer of inert material, or the cup may be made so deep that the fused ceramic material cannot flow into and fill same.

But I regard this invention as particularly applicable 'to protecting the ends of compound metal anchor pins.

In the accompanying illustration I have shown, more or less diagrammatically, certain means and materials useful in performing the described process, and products thereof.

In this showing :Figure 1 shows a crosssection on a greatly enlarged scale of compound wire having no metallic 'union be-.

tween core and sheath; Fig." 2 is asimilar section of metallically united wire; Fig. 3 is a vertical section of a double-headed tooth pin made of either wire; Fig. 4 is a vertical section of a single-headed pin made of the metallically united wire and intended to be bent in subsequent assemblage with a tooth plate; Fig. 5 is a similar section of a similar pin showing the end deeply cupped to prevent tooth plastic gaining access to the bare spot of strong metal; Fig. 6 is a section of a mold-form for flat-backed teeth carrying a compound metal wire pin in position; Fig. 7 is a similar section after application of a protective layer to the bare end of the core metal of the pin of Fig. 4; Fig. 8 shows the same mold full of compacted tooth plastic isolated from the bare end by the isolating layer; Fig. 9 shows a section through a complete fiat-backed tooth and anchor wire showing the tooth plastic, pin and intermediate shielding layer in position; Fig. 10 shows the same tooth after application of a drop of gold solder or the like to the outer head of the pin; and Fig. 11 shows a tooth carrying a compound metal pin having the inner endof the core isolated as before and having the outer end of the pin bent ready for assemblage with a tooth plate.

In Fig. 1, element 1 is a strong metal core which may be ofany of the ordinary strong metals, depending on the fusing point of the ceramic employed, such as iron, steel, alloy steels, nickel, nickel-steel, cobalt, etc., while 2 is an outer sheath of platinum or other noble metal or alloy, but preferably platinum. For the present purposes, it is not necessary to harden the platinum -with iridium. This compound metal element may be produced by simply assembling core and sheath and drawing them down together into wire, hot or cold. This, although it will produce no metallic union between sheath and core will still easily produce a form of compound wire suitable for use for double headed pins (Fig. 3) in which the double heading will produce a locking engagement between the two metals at each end of the pin, giving a certain amount of mechanical strength. The ease in production however is at the expense of economy since the platinum must be thick enough to have mechanical strength of its own, and this involves both an extra expense for platinum and the drawback that an ounce of wire will not make so many pins, an ounce of platinum roughly speaking, having only about a third the volume of an ounce of the common strong metals, such as nickel, iron, etc., so that the more platinum is used in the compound metal the fewer pins it will make per ounce.

Fig. 2 shows a similar section of a compound metal having a metallic union between sheath and core, indicated by. black line 3 which may either represent a certain welding or alloying between sheath and core metals or the presence of a film-like layer of a linking metal, such ascopper, silver or gold.

In Fig. 3, the compound wire which may be of either of the described types, has been formed intoa double headed pin with the sheath metal partly drawn over the core at the ends but still leaving bare spots 4 and 5 at the upper and lower ends.

Fig. 4 shows a single-headed pin intended after baking in the tooth to be bent as shown in Fig. 11 to form an anchorage in the tooth plate. This pin can only usefully be made of the described welded or metallically united compound metal since a platinum tube not so united to the core cannot well be bent unless of comparatively greatthickness. WVhile in such weld-united metal the platinum may be completely arched over the headed end, it is easier to form it, as shown, incompletely so arched with a bare spot of core existing. If desired, in forming the head of the pin the headmay be given a cup-like form, bringing the bare spot of core metal at the bottom of a comparatively deep recess, as shown in Fig. 5. In use this recessing prevents, more or less eflectually, the tooth plastic reaching and contacting with the core metal.

In Fig. 6, a pair of double-headed pins 6 made of either type or metal, is shown positioned in the bottom of a tooth mold 7 and extending thereinto. In Fig. 7, these pins are shown with the inner end of the core covered with a protective layer of alumina or the like inert mineral matter 8. This layer may be applied by hand, as by painting with a camels hair pencil carrying a paste of the mineral matter with water and excipient or as by applying it as a dry powder. With mold and pin in the position shown with the head upward, the dry powder will rest in place. The inert spacer may of course be applied by any suitable apparatus (not shown). After application, the mold is filled as usual (see Fig. 8) with the body of plastic material 9, compressed into place. The spacmg layer prevents it, however, coming into actual contact with the bare spot at the end of the compound pin.

Fig. 9 shows the completed tooth so manufactured after firing. It will be noted that the inner end of the core metal is still isolated or spaced away from the body of the tooth. Wheremagnesia'or other very basic oxids are used in lieu of alumina, there may be a line of merger indicated by 10 between the body of spacer and the body of acid tooth plastic, but the acid tooth plastic proper does not come into contact with the base metal. With a tooth so formed, the outer end of the pin still carries a bare spot which may usefully be sealed in; and particularly where the metal is of the type of that shown in Fig. 1 since therewill be a seam or line of non-union between the metals into which corrosive agents may pass and since this type of metal is not as strong as is desirable. This bare s 0t may next be covered with a drop of go d solder or other suitable solder, shown as 11, (see Fig. 10). This both seals .the orifice and, consequently, the seam, and adds much to the mechanical strength of the pin. With compound metal of the type shown in Fig. 2 this precaution is not so necessary, since the metal has ample mechanical strength and there is no seam between core and sheath.

-In Fig. 11, a tooth carrying a singleheaded pin of metal of the type of that shown in Fig. 2 is illustrated, the pin being bent at its outer end to enable it to be anchored in a back plate in the usual manner. No solder sealing of the outer end of this metal is required, no seam existing, the pin being amply strong and the platinum being usually sufliciently arched over the bare end of the core, particularly where the metal has been cut with round-edged or obtunding cutters. metal over a simple cut as compared with the difiiculty of archingit over a pin head. The end may be sealed with solder but it is not necessary. The bare end of the base It is easy to arch the metal core may be isolated from the active hot tooth plastic in other ways, as by laying a leaflet of platinum foil upon it, by com pletely arching the platinum sheath over such bare end, etc., but the use of little inert mineral material such as alumina as a spacing layer, is simple, economical and conven ient.

What I claim is 1. The process of making an artificial tooth provided with a cored compound metal anchor element with a core of corrodible metal which comprises placing said anchor element in position, covering the exposed portions of the core with a protective layer of inert mineral matter, molding a tooth plastic about the anchor element and firing the molded tooth.

2. The process of making an artificial tooth provided with a cored compound metal anchor element with a core of corrodible metal which comprises covering the exposed portions of the core with a protective layer comprising alumina, molding atooth plastic about the anchor element and firing the molded tooth.

3. As a new article of manufacture, an artificial tooth comprising a body of fired ceramic material free of undesirable discolorations and deformations, and a compound metal pin inset in said ceramic material prior to firing and locked in place thereby, said pin comprising a noble metal sheath and a strong metal core, and the inset end of said core being spaced away from said ceramic material by inert material.

In testimony whereof, I afiix my signa ture in the presence of witnesses.

BYRON fE. ELDRED.

Witnesses:

A. M. SENIOR, JOHN A. RILEY. 

